Discharge bar for neutralizing static electricity



Nov. 18, 1930. w CHAPMAN 1,782,340

DISCHARGE BAR FOR NEUTRALIZING STATIC ELECTRICITY Filed April 6, 1.929

Patented Nov. 18, 1930 UNITED STATES @E'FECE WILLIAM HENRY CHAPMAN, OF PORTLAND, MAINE, ASSIGIIOF, T0 CHAPMAN ELECTRIC NEUTRALIZER COMPANY, OF PORTLAND,

MAINE, A CGBPORATZOII OF MAINE Application filed April 6, 1929.

My present invention relates to certain improvements in discharge bars of systems for neutralizing static electricity generated in the process of manufacture or the printing of paper textile fabrics or the like, whereby the static charge on these materials is neutralized by the discharge upon them of high voltage alternating charge through the air.

Under many operating conditions these bars are apt to become coated by dusty escapements from the materials being used whereby the efiiciency of the apparatus is decreased. As a characteristic instance which has caused much difficulty, and in fact seemed previously to have precluded the satisfactory use of neutralizers, I cite the instance of printing where a metallic powder is employed.

The use of bronze powder has been particularly troublesome as this powder collects on the distributor bar. All other neutralizer bars that have ever been produced heretofore are weakened in their useful activity by the deposit of bronze powder upon them due to the fact that the bronze coated surfaces form an avenue of escape for the charge that should be allowed to escape only at the discharge points.

Any deposit of bronze powder on my new bar virtually increases the surface of the inductive sleeves adding an extra charge which can only escape through the discharge points and makes them all the more active, while at the same time the inducingcharge on the. rod is prevented from escaping by its dust tight enclosure. This dust or powder furthermore was very penetrating and worked its way into the crevices between the various parts and could only be removed with considerable difliculty and at considerable expense.

Furthermore, the protection of the bar connections proved difficult under such conditions, as these connections usually had to be of certain length because the bar itself is necessarily disposed closely adjacentthe travelled sheet and therefore at some distance from the current source.

Furthermore, a common difficulty in the mounting of the discharge points has been Serial No. 353,219.

in getting them tightly mounted in proper spacing along the distributor bar.

In addition to the foregoing, the actual discharge points if unprotected were apt to be bent or broken. To prevent this I have for certain instances provided guards, but these guards while successful under certain conditions introduced disturbing factors and in such a case as that cited where metallic dust deposited, these guards becoming coated interfered with the localization of the discharge at the discharge point which in practice is required to be a very fine point.

The foregoing diff culties have been overcome by me in accordance with my present invention, which I will now describe in detail, although I do not wish to be limited thereby except as I shall so indicate.

As illustrative of my invention, I have shown in the accompanying drawings, apparatus in accordance with the principles thereof and a simple and highly cfficient type well adapted to a great variety of usages and capable of production at very reasonable cost.

Throughout the specification and drawings' like reference characters are employed to indicate corresponding parts, and in the drawings:

Fig. 1 is a general view of a bar installation.

Fig. 2 is a fragmentary view of a bar in accordance with my invention partly sectioned to indicate the construction thereof.

Fig. 3 is a partial section through the dis charge point holder.

Fig. iis a section on the line 4-4, of F ig. 1.

Figs. 5 and 6 are respectively a side and plan view of a modified form of point.

I have indicated at B a rod or bar preferably a rigid conductor member for which purpose I may use a steel rod of the desired diameter and adapted to be electrically connected to an alternating current generator G and transformer having a high tension secondary coil S one end of which is connected to the cable E leading to the neutralizer bar B and the other end to the ground X.

Suitable supports are provided for the bar as indicated by the hangers J which are pref- T erably made of wood or fibre, preferably suspended from the ceiling or at some point sufficiently distant to be beyond the range of the flying dust, and are provided at their lower ends with clamp members K of like matewhich I will later explain. For this purpose a rubber or composite tube as of rubber and fabric may be employed. As shown it should be of such length as to extend up over the conductor cable E, and as such cable is usually bent adjacent the bar, the matter of flexi bility is one of great convenience. At the opposite end of the bar B the tubular sheathing extends for a short distance and receives an insulating plug D of rubber or hard fibre to which the end of the tubing is tightly clamped as by'a clampG in order 'toget a perfectly dust tight joint and to hold the parts contained snugly in place.

At the conductor end the cable E enters the tube A. This cable preferably snugly fits the bore of the tube A or is made to do so'so that it can be clamped by a clamp G to make it a perfectly dust proof joint. The end of the cable E is provided with a spring F for making contact with the end of the bar B, the parts being assembled under such compression of the spring as will insure contact at all times and take up any expansion or contraction or compensate for any adjustment or movement made if the connections are flexed.

Over the tube A and spaced along the bar '3 I arrange my discharge members. Of

these I have shown two characteristic types. For installations involving, for example, the metallic dust, I prefer a'discharge member shown in the sectional view, Fig. 3. In this I provide an inductor band or strap 1 having a pair of ears. 2' apertured to receive, the shank of a bolt-like member M. The shank of this member is threaded to receive a tubular member N which has a threaded portion adapted to receive the bolt shank locked by nut N and a reduced bore leading therefrom to its opposite end. This member carries the discharge point P which is preferably formed of wire, its base being wound in a conic spiral coil P formed with an enlarged base portion P? adapted to be clamped in a larger portion of the bore by the end of the bolt shank. This makes possible a very tight joint and an advantageous support for the point at its outer end. The bore of the member N is flared out as indicated at n so as to permit a free fiexation of the portion P of the oint.

T e point P if accidentally struck will therefore yield resiliently but will spring back in place and as the point is made of rather fine wire it can be, if actually bent, readily straightened out. As indicated, such a point usually lies parallel with the run of the paper as indicated in Fig. A and pointing in the direction of movement of the paper. The points, however, may be readily adjusted by simply loosening the bolt member hi and slipping the band on the envelope A. It will be noted that these point clamps can be set up tightly owing Lo the compressibility'of the envelope A so that when onceadjusted they tend tohold in place both on account of the tightness-oftheir clamping and also due to their slight embedding in the surface of the envelope A. r

In tie form shown in Figs. 5 and 6 Iform the inductor strap J with one end projecting farther thanthe other to form a point B. Over these I place a pairof guards Qof'insulating material beveled ofion their inner faces as at q and held by a bolt S. This'type of point I find very satisfactory except in the presence of du-stas before indicated.

As hereinbefore stated, the .devices shown are illustrativebut they do represent very practical and convenient apparatus; .Such structure, however, may be variously modified and variously combined and various materials used or substituted, and all without departing from the spirit of my invention as defined in the following claims.

\Vhat I therefore claim and desire-to secure by Letters Patent'is:- i

1. A discharge bar for neutralizing static electricity comprising a conductor member, an electrical connection therefor, a compressible insulating sheath thereon and compressibly adjustable discharge members mounted on said sheath.

2. A discharge bar for neutralizing static electricity comprising a rigid conductor member, an electrical connection therefor, a compressible insulating sheath thereon and compressibly adjustable. discharge members mounted on said sheath.

8. A discharge member for a static nan tralizer comprisinga tubular holder having an enlarged and threaded bore at one end, a wound point member comprising a conic spiral part having an enlarged base" and a free apex point, said base being lodged in said enlarged bore, and a threaded member compressibly engaging said enlarged end.

A. A holder for the discharge point of a static neutralizer, said discharge pointxhaving an enlargement constituting a base comprising a tubular member having an enlarged and threaded bore at one end and flaring mouth at the other, and a threaded member entered in said enlarged bore and adapted to compressibly clamp the base of a discharge point lodged in said tubular member. V

5. A discharge bar for neutralizing static ire,

electricity comprising a conductor bar, a compressible insulating sheath thereon, a capacitively coupled sleeve, means for clamping it about the bar, and a resiliently mounted discharge point connected to said sleeve and comprising a conic spirally coiled base and a tip member projecting therefrom.

6. A capacitively coupled discharge member for a neutralizer bar comprising a sleeve of conducting material, means for clamping it about the bar, and a discharge point having a conic spirally coiled base connected to said sleeve and a tip member projecting therefrom.

In testimony whereof I aflix my signature.

WILLIAM HENRY CHAPMAN. 

